Q.

The figure shows a liquid of given density flowing steadily in a horizontal tube of varying cross-section. Cross-sectional areas at A is 1.5 cm2, and B is 25 mm2. If the speed of liquid at B is 60 cm/s, then (PA-PB) is

(Given PA and PB are liquid pressures at A and B points. Density ρ=1000 kg m3.  

A and B are on the axis of the tube                                              [2023]

1 175 Pa  
2 27 Pa  
3 135 Pa  
4 36 Pa  

Ans.

(1)

From continuity theorem A1V1=A2V2

1.5×V1=25×10-2×60

V1=25×60×10-2×101.5=10 cm/s

By Bernoulli's theorem

P1+12×1000×(0.1)2=P2+12×1000×(0.6)2

P1+5=P2+12×1000×36×10-2

  P1-P2=175 Pa